Returns previous row or null if it is the very first row.

<div class="definition">
     prevRow(index, [colIndex], [numRows=1])
</div>

<div class="arguments">
    <table>
        <tr>
            <td>index</td>
            <td><b>integer</b>, row index in records array</td>
        </tr>
        <tr>
            <td>colIndex</td>
            <td><b>integer</b>, <i>optional</i>, column index (it will skip the row is colspan for this recrod more then 1)</td>
        </tr>
        <tr>
            <td>numRows</td>
            <td><b>integer</b>, <i>optional</i>, number of rows to advance</td>
        </tr>
    </table>
</div>
Returns integer or null.

<h4>Description</h4>

This method returns you previous row in the grid taking into account applied local search. If there is no previous row, it will
return null.
<div style="height: 10px"></div>

The first argument <span class="argument">index</span> is the index in the <a class="method" href="w2grid.records">.records</a> array.
The second optional argument <span class="argument">colIndex</span> is the index in the <a class="method" href="w2grid.columns">.columns</a>
array and if provided it might skip a row if corresponding cells have cellspan in a way that it results for that cell to
be hidden.
<div style="height: 10px"></div>

If you have grid defined in the following way:
<textarea class="javascript">
let grid = new w2grid({
    name: 'grid2',
    columns: [
        { field: 'recid', text: 'ID', size: '50px' },
        { field: 'lname', text: 'Last Name', size: '30%', editable: { type: 'text' } },
        { field: 'fname', text: 'First Name', size: '30%', editable: { type: 'text' } },
        { field: 'email', text: 'Email', size: '40%', editable: { type: 'text' } },
        { field: 'sdate', text: 'Start Date', size: '120px', editable: { type: 'date' } },
        { field: 'edate', text: 'End Date', size: '120px', editable: { type: 'date' } }
    ],
    records: [
        { recid: 1, fname: 'John', lname: 'doe', email: 'vitali@gmail.com', sdate: '1/3/2012' },
        { recid: 2, fname: 'Stuart', lname: 'Motzart', email: 'jdoe@gmail.com', sdate: '2/4/2012' },
        { recid: 3, fname: 'Jin', lname: 'Franson', email: '--', sdate: '4/23/2012' },
        { recid: 4, fname: 'Susan', lname: 'Ottie', email: 'jdoe@gmail.com', sdate: '5/3/2012' },
        { recid: 5, fname: 'Kelly', lname: 'Silver', email: 'jdoe@gmail.com', sdate: '4/3/2012' },
        { recid: 6, fname: 'Francis', lname: 'Gatos', email: 'vitali@gmail.com', sdate: '2/5/2012' }
    ]
});
</textarea>

You can do:
<textarea class="javascript">
w2ui['grid2'].prevRow(3);
</textarea>